Its a UV LED flash light from Amazon for about ~14$
Originally got it for my nephew to go scorpion hunting in the evenings (yeah they really do glow!)
I also found it useful for inspecting for other things that "glow" under UV...
(tried it in a Starbuck's restroom, not pretty)
It is also good for finding leaks or previous ones in my case.
I had my AC serviced when I first got my truck and some of the die is still visible in the photo...

You can get dies to add to the AC and also to the oil to find leaks...
The attached pictures are of the UV flashlight
a regular or ambient light picture
and one with the UV light shined at the charge port of my AC for my Tahoe...
notice the green glow on the cap ( probably where it bled over when they charged it after changing the valve, as it was leaking....

 

Make a nice Christmas stocking stuffer. Any model or P/N info?

 

The description is: 395 nM UV Ultraviolet 51 LED flashlight / Blacklight 3 AA
part no. 7202UV395
price on Amazon at this writing is $17.50

Technical Details
Emits 395 nanometer wavelength, hunting scorpions and minerals!
hotel room inspection, rodent contamination
Essential tool for law enforcement, postal inspections, customs, medical forensics, HVAC repair
51 UV LED bulbs allow to cover a larger area
Uses 3 AA Standard Alkiline Battery which cost same price as AAA, but last 3 times longer than AAA

http://www.amazon.com/Ultraviolet-LE...1475658&sr=1-1

 

Thanks for the info. Now I can find all of those uranium filled marbles I lost.